big vs giant

big is not a noun while giant is a noun.

Word	Noun	Adjective	Verb	Adverb
big	No	Yes	No	Yes
giant	Yes	Yes	No	No

big (noun)	giant (noun)
	any creature of exceptional size
	an unusually large enterprise
	a very bright star of large diameter and low density (relative to the Sun)
	someone that is abnormally large and powerful
	a person of exceptional importance and reputation
	an imaginary figure of superhuman size and strength; appears in folklore and fairy tales
	a very large person; impressive in size or qualities

big (adjective)	giant (adjective)
above average in size or number or quantity or magnitude or extent	of great mass; huge and bulky
conspicuous in position or importance
given or giving freely
generous and understanding and tolerant
marked by intense physical force
significant
prodigious
serious or severe
loud and firm
(of animals) fully developed
in an advanced stage of pregnancy
feeling self-importance
exhibiting self-importance